This invention relates to the production of coke in a non-recovery type coke oven, and more particularly to apparatus for quenching the coke outside the coking chamber and at the same time to incinerate the smoke and effluent from the coke while located outside the coke oven chamber during the quenching process.
Currently, the chief method for producing coke is accomplished by a by-product or retort process wherein air is excluded from the coking chamber and all volatile products liberated during the distillation process are recovered as gas and other coal by-product chemicals. In recent years, coke producers using the by-product process have had difficulty disposing of the recovered coal chemicals on a profitable basis, particularly since many of the same or equivalent chemicals are recovered incident to the refining of petroleum products. The cost of producing coke by the by-product method has increased because the sale of chemicals is now less profitable.
Emissions of smoke and distillation gases unavoidably occur in the retort process. Cracks in the oven masonry, failure of coke oven doors to properly seal the coke oven chamber and the entire period of time while coke is pushed from the oven chamber permit the escape of effluent into the atmosphere. After the coke is pushed from an oven chamber, it is transported by coke quenching cars to a tower where it is quenched with water. Thus, after the coke is pushed and until it is quenched, environmental pollution is a serious problem.
A much older coking process is carried out in a non-recovery type coke oven which is sometimes referred to in the art as a beehive coke oven. A battery of such coke ovens were build adjacent each other and operated by pulling from alternate ovens on alternate days, the masses of coke. The heat from the side walls of the hot coke ovens and any residual heat retained in a newly-charged coke oven was usually sufficient to ignite the coal in the newly-charged coke oven. The cycle for production of coke by each oven chamber was about 72 hours. A non-recovery type coking process provides important features and advantages, particularly a more economical process. The coke ovens are less costly and require a minimum of ancilliary equipment, particularly because facilities are not required for treating by-products of the coking process. However, smoke, together with other unburnt volatile products, escaped during the coking process into the atmosphere. The emissions were a source of environmental pollution whereby the non-recovery type coking process has been largely done away with in view of current environmental standards.
At the end of the coking process, the brickwork used to close an opening in a wall of the non-recovery coke oven is removed and the coke is quenched by moving spray pipes into the oven chamber. After quenching, the coke is drawn from the oven chamber either manually or by suitable machinery for transport to a wharf where it is stored for classification and then shipment. Smoke and other unburnt volatile products during quenching were another source of environmental pollution.
In U.S. Pat. No. 4,045,299, assigned to the same Assignee as the present invention, there is disclosed a smokeless and non-recovery type coke oven wherein the distillation gases liberated during the coking process are conducted from the space above the coal charge downwardly along passageways in the side walls forming the oven chamber into a sole heating flue. Primary air is fed into the oven chamber to maintain combustion within the space above the coal charge. Secondary air is fed into the downcomers for combustion of gases in the sole heating flues and in a tandem arrangement of ignition chambers located downstream therefrom. The ignition chambers are positioned between two such coke ovens to incinerate any unburnt distillation products received from the sole heating flues of the two oven chambers. Additional quantities of secondary air for combustion are injected into the ignition chambers and a burner is used to maintain a predetermined minimum temperature at all times in the ignition chamber to insure incineration of the smoke gases passing therethrough. Waste gases are conducted from the ignition chambers by a horizontal duct to a stack.
In application Ser. No. 788,284, filed Apr. 18, 1977 and assigned to the same Assignee as the present invention, there is disclosed an automatic control for a coking process in a smokeless and non-recovery type coke oven. A negative draft pressure of between 0.15 and 0.17 inch water gage is maintained at all times on each of the two oven chambers while supplies of secondary air fed into the downcomers are progressively decreased so as to maximize combustion of distillation gases in the downcomers and the sole heating flues as well as the ignition chambers. Such a method of operating the non-recovery type coke oven provides an increased coking rate without polluting the atmosphere with effluents including the distillation gases given off from the coal charge in the oven chambers.